Organosilicon compounds, such as for example silanes or siloxanes, are frequently used in polymer compositions as water repellants. There are available additive material in the prior art which when added to the dry cement will impart the hydrophobic property.
There are prior art which describe additive compositions in the form of emulsion.
U.S. Pat. No. 4,648,904 reissued as U.S. RE33759 (hereinafter referred to as 759'): 759' discloses an aqueous emulsion of (a) a hydrolyzable silane. The composition in the prior art is in the form of emulsion which leads to a drastic reduction in the hydrophobicity property.
WO2011087829A1 describes aqueous emulsions of certain alkylalkoxysilanes and cationic alkoxysilanes that provide water proofing properties to a variety of substances, and in particular to masonry or concrete surfaces.
There are many issues with the prior art additive composition, e.g. the additive composition in the form of emulsion, the reactive alkoxy group present in the silane molecule reacts with each other in presence of water and forms a cross linked structure and thus becomes unreactive overtime. Hence the reactivity with the silicate molecule of the cement deteriorates, thus do not render proper hydrophobicity.
US20110201727A1 describes additive composition in the form of liquid or solid which is obtained by silane modified additives obtained by condensation of one or a plurality of silanes. But condensing silanes by mixing with an aqueous solvent in the presence of water-soluble polymers will have similar issue of losing the reactive alkoxy sites in the silane molecule. Thus, decreasing the final hydrophobic property of the material in which it is added.
There are prior art that the additive composition in the form of granulated hydrophobing additive. WO 2008/062018 describes a process for preparing a granulated hydrophobing additive for cementitious material in which an organosilicon component and a binder polymer are applied to a particulate carrier from aqueous emulsion.
WO2013166280A1 describes a process for increasing the hydrophobicity of a porous product by treating the product, or a composition providing for the product, with a water repellent material, characterized in that the porous product or a composition providing the product, is treated with an aqueous suspension of microcapsules where the microcapsules comprise a water repellent organosilicon core material selected from an organosilane, a partially condensed organosilane and a branched siloxane resin, and a shell of a silicon-based network polymer comprising silica units.
The granular hydrophobing additive when added to the cement forms a dry cementitious powder mixture, and when water is added to the dry cementitious powder mixture the active silane slowly get released but in the meantime due to the presence of water the active sites of cement start reacting with each other thus inhibiting proper attachment of active site of silane molecule with the active site of cement. Thus due to this issue, the hydrophobicity is not properly and uniformly achieved in the final product.
All the compositions known in the art which are in the emulsion form deteriorate over time on storage.
Thus there is a need of a proper solution that will impart proper hydrophobicity to the porous material when used as an additive composition and to provide compositions containing organosilicon compounds in a storage-stable form.
The present inventors have surprisingly found certain combinations of alkylalkoxysilanes and non-ionic emulsifier that self-disperse into water to form an emulsion without the need to use co-surfactants, nor any type of energy intense emulsifying equipment. The present emulsions provide water proofing properties to a variety of substances, and in particular to masonry or concrete surfaces, without requiring the addition of cure catalysts, the cure catalyst may be required for other applications like coating or film formation.